new and rare Crustacea from Scotland. 139 



Dottom here, in mid-channel, is composed largely of irregular 

 lumps of hardened mud, formed of the agglutinated tubes of 

 a species of Sabella. Some of this mud was dredged and 

 carefully washed ; the water in which the mud was washed 

 was then passed through a muslin sieve, and when the contents 

 of the sieve were afterwards transferred to a bottle of sea- 

 water numbers of the little Amymone nigrans appeared as 

 blackish specks swimming about, and their peculiar move- 

 ments characteristic of this remarkable genus formed an 

 interesting study. 



Remarks. Though Amymone nigrans does not agree with 

 any described species known to us, it is yet possible that it 

 may be the form ascribed by Boeck to Amymone sphcerica, 

 Claus, and which he described as having the outer branches 

 of the swimming-feet two-jointed. It is supposed by some 

 authors that Boeck has somehow mistaken the number of 

 joints in the outer branches, because the outer branches of the 

 second and third as well as of the fourth pair of swimming- 

 feet in Amymone spharica are all three-jointed, and certainly 

 the Scottish specimens of what we believe to be that species 

 have three-jointed outer branches to the second and third 

 pairs ; but the discovery of Amymone nigrans will tend to 

 show that Boeck's description may be right after all, and that 

 the mistake was made in ascribing to Amymone sphmrica, 

 Claus, a form that was probably quite distinct from that 

 species. But, whatever be the explanation, there can be no 

 doubt that the form we have here described as Amymone 

 nigrans has the outer branches of the second and third pair of 

 feet in both sexes two-jointed. 



In all the specimens of Amymone sphcerica examined by us 

 we observe that each stylet is furnished with a broad lancet- 

 shaped seta, the breadth of each seta at the widest part being 

 equal to about two fifteenths of the length. We have not 

 observed these peculiar setee on any other species of A mymone. 



Ameira exilis *, sp. n. 

 (PI. VIII. figs. 18-20 J PI. IX. figs. 1-3.) 



Body elongate, slender. Length 1*4 millim. [-^ of an inch) . 

 Anterior antennse of the female nine-jointed, somewhat longer 

 than the first body-segment and sparingly setiferous, and 

 with the seventh and eighth joints very small ; the lengths of 

 the joints are nearly as shown in the formula — 



13 . 18 . 13 ■ 10 . 8 . 9 . 3 . 3 ■ 12 

 1 2 3 456789' 



♦ Exilis, slender. 



